1. Field of the Invention
The present invention relates in general to fault tolerant network arrangements, and more particularly to a fault permission network arrangement in which a dual receive dual transmission (referred to hereinafter as DRDT) network is used to first process a fault upon occurrence of the fault which is then detected through an individual function.
2. Description of the Prior Art
Generally, a large-scale system comprises modules by functions and an interface network which interconnects the modules to one another. However, the system cannot perform a normal operation when a fault occurs in the interface network.
For example, a distributed system comprises an interface network for interconnecting computers to one another. A fault may occur in the interface network. The occurrence of the fault affects the entire operation of the system, so that a normal function cannot be performed by the system. In order to prevent this outcome and to thus enhance the reliability of the system, a dual interface network may be employed in the system.
FIG. 1A is a view illustrating an arrangement of a conventional dual fiber distributed data interface (referred to hereinafter as FDDI) network under a normal condition and FIG. 1B is a view illustrating an arrangement of the conventional dual FDDI network upon occurrence of a fault. The conventional dual FDDI network comprises a dual line. Upon the occurrence of the fault at a certain node, the remaining nodes are rearranged through a single line so that they can normally communicate with one another. Namely, under the normal condition, the communications are performed in the opposite directions through the two lines as shown in FIG. 1A. If the fault occurs at a certain node 12D, the remaining nodes 12A-12C are rearranged through the single line as shown in FIG. 1B. As a result, the normal nodes can communicate with one another. In this manner, the conventional dual FDDI network must first detect the fault to process it. With the fault detected, the remaining nodes are rearranged through the single line, for message transmission and reception.
However, the above-mentioned conventional dual FDDI network with the dual line has a disadvantage in that the entire system cannot perform the normal operation if the fault occurs again at one of the normal nodes or a link after the single line-rearrangement.